The present invention relates, in general, to the field of integrated circuit ("IC") devices. More particularly, the present invention relates to a current sensing differential amplifier with high rejection of power supply variations of particular utility with respect to differential main amplifiers utilizing multiple power supplies such as those used in certain integrated circuit memory devices, including synchronous dynamic random access memories ("SDRAMs").
In certain differential main amplifier designs, the input signal differential voltage is based on a regulated voltage supply while the feedback and switching speed is based on that of an unregulated supply voltage source such as V.sub.cc. This renders acceptable function in a synchronous system problematic in light of potential variations in the unregulated supply voltage source. For example, at increased levels of V.sub.cc, too much feedback may be induced in the amplifier compressing the differential from the sense amplifier input signal and causing the amplifier to be excessively fast when reading data. This can result in an erroneous latching of data in a synchronous DRAM device. Moreover, the compression of the differential signal also introduces the possibility of noise coupling on the signals thus allowing for the potential amplification of the wrong data.